1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
// atomic_int.h
// atomic wrapper for unsigned
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#if defined(_WIN32)
# include <windows.h>
#endif
namespace mongo {
struct AtomicUInt {
AtomicUInt() : x(0) {}
AtomicUInt(unsigned z) : x(z) { }
operator unsigned() const { return x; }
unsigned get() const { return x; }
inline AtomicUInt operator++(); // ++prefix
inline AtomicUInt operator++(int);// postfix++
inline AtomicUInt operator--(); // --prefix
inline AtomicUInt operator--(int); // postfix--
inline void zero();
volatile unsigned x;
};
#if defined(_WIN32)
void AtomicUInt::zero() {
InterlockedExchange((volatile long*)&x, 0);
}
AtomicUInt AtomicUInt::operator++() {
return InterlockedIncrement((volatile long*)&x);
}
AtomicUInt AtomicUInt::operator++(int) {
return InterlockedIncrement((volatile long*)&x)-1;
}
AtomicUInt AtomicUInt::operator--() {
return InterlockedDecrement((volatile long*)&x);
}
AtomicUInt AtomicUInt::operator--(int) {
return InterlockedDecrement((volatile long*)&x)+1;
}
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
// this is in GCC >= 4.1
inline void AtomicUInt::zero() { x = 0; } // TODO: this isn't thread safe - maybe
AtomicUInt AtomicUInt::operator++() {
return __sync_add_and_fetch(&x, 1);
}
AtomicUInt AtomicUInt::operator++(int) {
return __sync_fetch_and_add(&x, 1);
}
AtomicUInt AtomicUInt::operator--() {
return __sync_add_and_fetch(&x, -1);
}
AtomicUInt AtomicUInt::operator--(int) {
return __sync_fetch_and_add(&x, -1);
}
#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
inline void AtomicUInt::zero() { x = 0; } // TODO: this isn't thread safe
// from boost 1.39 interprocess/detail/atomic.hpp
inline unsigned atomic_int_helper(volatile unsigned *x, int val) {
int r;
asm volatile
(
"lock\n\t"
"xadd %1, %0":
"+m"( *x ), "=r"( r ): // outputs (%0, %1)
"1"( val ): // inputs (%2 == %1)
"memory", "cc" // clobbers
);
return r;
}
AtomicUInt AtomicUInt::operator++() {
return atomic_int_helper(&x, 1)+1;
}
AtomicUInt AtomicUInt::operator++(int) {
return atomic_int_helper(&x, 1);
}
AtomicUInt AtomicUInt::operator--() {
return atomic_int_helper(&x, -1)-1;
}
AtomicUInt AtomicUInt::operator--(int) {
return atomic_int_helper(&x, -1);
}
#else
# error "unsupported compiler or platform"
#endif
} // namespace mongo
|
